An Etymological Dictionary of the German Language/klabastern

by Friedrich Kluge

klabastern, vb., ‘to run noisily,’ ModHG. only; orig. a LG. term; in consequence of the entire absence of the word in the earlier periods of the languages its origin is dubious; it is most probably akin to OHG. klaphôn, MidHG. klaffen, ‘to clatter’; AS. clappian, E. to clap.